TGF-β1-induced apoptosis in retinal endothelial cells is implicated in retinal vein occlusion.

Retinal vein occlusion (RVO) is a serious vascular condition that impairs vision due to retinal endothelial cell injury and apoptosis. This study aimed to identify key molecular pathways and therapeutic targets involved in RVO pathogenesis. Transcriptomic analysis of the retinal tissues from a mouse RVO model was performed to identify differentially expressed genes and co-expression modules associated with RVO. Protein-protein interaction network analysis pinpointed putative hub genes. In vitro experiments using human retinal microvascular endothelial cells (HRMECs) validated the involvement of identified genes/pathways in apoptosis induced by oxygen-glucose deprivation/reperfusion (OGD/R) and UV exposure. Gene expression was assessed by RT-qPCR, while protein levels and phosphorylation were measured by ELISA and Western blotting. Apoptosis was evaluated using flow cytometry, and reactive oxygen species (ROS) were quantified using a fluorescence-based assay. A total of 392 genes were identified as putatively involved in RVO-associated apoptosis, enriched in MAPK, TGF-β and other signaling pathways. Among top hub genes, TGF-β1 emerged as a central regulator whose expression and signaling (pSmad2/3) increased after OGD/R induction or UV exposure in HRMECs. TGF-β1-induced HRMEC apoptosis was mediated by p38/JNK activation. Similar effects were observed for OGD/R and UV triggering TGF-β1-dependent p38/JNK signaling and apoptosis. Pharmacological inhibition of TGF-β signaling attenuated the apoptotic and oxidative stress responses induced by OGD/R and UV exposure. This study elucidates TGF-β1 as a crucial mediator of retinal endothelial injury through p38/JNK-induced apoptosis, suggesting TGF-β1 pathway inhibition as a potential therapeutic strategy for RVO.